Bacterial colonization of the upper respiratory tract and its association with acute lower respiratory tract infections in Highland children of Papua New Guinea

Pneumococcus and the stress-gradient hypothesis: A trade-off links R0 and susceptibility to co-colonization across countries

Modern molecular technologies have revolutionized our understanding of bacterial epidemiology, but reported data across studies and different geographic endemic settings remain under-integrated in common theoretical frameworks. Pneumococcus serotype co-colonization, caused by the polymorphic bacteria Streptococcus pneumoniae, has been increasingly investigated and reported in recent years. While the global genomic diversity and serotype distribution of S. pneumoniae have been well-characterized, there is limited information on how co-colonization patterns vary globally, critical for understanding the evolution and transmission dynamics of the bacteria. Gathering a rich dataset of cross-sectional pneumococcal colonization studies in the literature, we quantified patterns of transmission intensity and co-colonization prevalence variation in children populations across 17 geographic locations. Linking these data to an SIS model with cocolonization under the assumption of quasi-neutrality among multiple interacting strains, our analysis reveals strong patterns of negative co-variation between transmission intensity (R0) and susceptibility to co-colonization (k). In line with expectations from the stress-gradient-hypothesis in ecology (SGH), pneumococcus serotypes appear to compete more in co-colonization in high-transmission settings and compete less in low-transmission settings, a trade-off which ultimately leads to a conserved ratio of single to co-colonization μ=1/(R0-1)k. From the mathematical model's behavior, such conservation suggests preservation of 'stability-diversity-complexity' regimes in coexistence of similar co-colonizing strains. We find no major differences in serotype compositions across studies, pointing to adaptation of the same set of serotypes across variable environments as an explanation for their differential interaction in different transmission settings. Our work highlights that the understanding of transmission patterns of Streptococcus pneumoniae from global scale epidemiological data can benefit from simple analytical approaches that account for quasi-neutrality among strains, co-colonization, as well as variable environmental adaptation.

Antimicrobial Resistance in Papua New Guinea: A Narrative Scoping Review

Antimicrobial-resistant bacterial infections are a known threat to the public health of low-income countries and are undercharacterized in Papua New Guinea. A scoping literature review of scientific peer-reviewed publications on antimicrobial resistance in Papua New Guinea was conducted, and their results were summarized. Many of the available data on resistant bacteria in Papua New Guinea have come from Port Moresby and Goroka and have been focused on Staphylococcus aureus, as well as important pediatric pathogens such as Streptococcus pneumoniae and Haemophilus influenzae. Progressive resistance to the commonly used antibiotics penicillin and chloramphenicol among most clinically important bacterial pathogens has prompted healthcare workers to adopt expensive broad-spectrum antibiotics. There is already evidence of resistance to newly adopted antibiotics among several Gram-negative organisms. Drivers of antimicrobial resistance in Papua New Guinea include a high burden of infectious diseases, inappropriate antibiotic prescription practices, poor regulation of antibiotics, incomplete adherence, substandard drug quality, and overcrowding of healthcare facilities. There is a lack of information on antimicrobial resistance among priority pathogens and from several important regions of Papua New Guinea.

Pneumococcal carriage, serotype distribution, and antimicrobial susceptibility in Papua New Guinean children vaccinated with PCV10 or PCV13 in a head-to-head trial

BACKGROUND

Children in Papua New Guinea (PNG) are at high risk of pneumococcal infections. We investigated pneumococcal carriage rates, serotype distribution, and antimicrobial susceptibility in PNG children after vaccination with 10-valent or 13-valent pneumococcal conjugate vaccines (PCV10; PCV13).

METHODS

Infants (N = 262) were randomized to receive 3 doses of PCV10 or PCV13 at 1-2-3 months of age, followed by pneumococcal polysaccharide vaccination (PPV) or no PPV at 9 months of age. Nasopharyngeal swabs (NPS) collected at ages 1, 4, 9, 10, 23 and 24 months were cultured using standard bacteriological procedures. Morphologically distinct Streptococcus pneumoniae colonies were serotyped by the Quellung reaction. Antimicrobial susceptibility was determined by Kirby-Bauer disc diffusion and minimum inhibitory concentration (MIC).

RESULTS

S. pneumoniae was isolated from 883/1063 NPS collected at 1-23 months of age, including 820 serotypeable (64 different serotypes) and 144 non-serotypeable isolates. At age 23 months, 93.6% (95%CI 86.6-97.6%) of PCV10 recipients and 88.6% (95%CI 80.1-94.4%) of PCV13 recipients were pneumococcal carriers, with higher carriage of PCV10 serotypes by PCV10 recipients (19.8%, 95%CI 12.2-29.5) than PCV13 recipients (9.3%, 95%CI 4.1-17.3) (p = 0.049). There were no other statistically significant differences between PCV10 and PCV13 recipients and children receiving PPV or no PPV. Nearly half (45.6%) of carried pneumococci were non-susceptible to penicillin based on the meningitis breakpoint (MIC ≥ 0.12 µg/mL), but resistance was rare (1.1%) using the non-meningitis cut-off (MIC ≥ 8 µg/mL). Non-susceptibility to trimethoprim-sulfamethoxazole (SXT) was common: 23.2% of isolates showed intermediate resistance (MIC 1/19-2/38 µg/mL) and 16.9% full resistance (MIC ≥ 4/76 µg/mL). PCV serotypes 14 and 19A were commonly non-susceptible to both penicillin (14, 97%; 19A, 70%) and SXT (14, 97%; 19A, 87%).

CONCLUSION

Even after PCV10 or PCV13 vaccination, children living in a high-risk setting such as PNG continue to experience high levels of pneumococcal colonization, including carriage of highly antimicrobial-resistant PCV serotypes. The study is registered with ClinicalTrials.gov (CTN NCT01619462).

Early clinical predictors for the prognosis of invasive pneumococcal disease

Background

Risk factors related to mortality due to invasive pneumococcal disease (IPD) have been unveiled previously, but early clinical manifestations of IPD based on prognosis remain uncovered.

Methods

The demographic characteristics, clinical features, serotype, antibiotic susceptibility, and outcomes of 97 hospitalized children with laboratory-confirmed IPD from Suzhou, China, were collected and analyzed retrospectively.

Results

The median age was 0.69 (0.49–1.55) years in the non-survivor group compared with 2.39 (0.90–3.81) years in the survivor group. The mortality of 97 children with laboratory-confirmed IPD was 17.5% (17/97), and 53.6% of them were aged less than 2 years. Pathogens were mainly from the blood and cerebrospinal fluid, and sepsis was the most frequent type. Statistically significant differences were found in hyperpyrexia, vomiting, anorexia, lethargy, poor perfusion of extremities, Hb level, and Plt count between the nonsurvival and survival groups. Further, the multivariate regression analysis showed that early signs, including hyperpyrexia, vomiting, anorexia, lethargy, and poor perfusion of extremities, were independent risk factors for the in-hospital mortality of children with laboratory-confirmed IPD. The mortality was also associated with antimicrobial sensitivity in pneumococcal isolates. The microbes in 1/17 (5.9%) children who were prescribed an antibiotic showed antimicrobial sensitivity in the nonsurvival group, compared with 21/80 (26.3%) children who survived. The most common serotypes identified were 6B (35.3%, 6/17), 14 (23.5%, 4/17), 19F (23.5%, 4/17), 19A (5.9%, 1/17), 23F (5.9%, 1/17), and 20 (5.9%, 1/17) in the nonsurvival group. The coverage of IPD serotypes of the 7-valent pneumococcal conjugate vaccine (PCV7) was 88.2% (15/17), while that of the 13-valent S. pneumoniae vaccine (PCV13) was 94.1% (16/17) of the coverage in the nonsurvival group.

Conclusions

Recurrent hyperpyrexia, vomiting, anorexia, lethargy, and poor perfusion of extremities in the early stage were independent predictors for the in-hospital mortality of children with laboratory-confirmed IPD. Appropriate use of antibiotics and PCV immunization were the keys to improve the outcome of IPD.

Preventative and medical treatment of ear disease in remote or resource-constrained environments

BACKGROUND

Important ear problems can affect the outer ear, the middle ear and the inner ear. Globally, the greatest burden of disease is due to ear conditions that are associated with otorrhoea and hearing loss.

METHODS

This study reviewed the literature on the prevention and treatment of common ear conditions that are most relevant to settings with high rates of ear disease and limited resources. The grading of recommendations assessment, development and evaluation ('GRADE') approach was utilised to assess interventions.

RESULTS

Accurate diagnosis of ear disease is challenging. Much of the preventable burden of ear disease is associated with otitis media. Nine otitis media interventions for which there is moderate to high certainty of effect were identified. While most interventions only provide modest benefit, the impact of treatment is more substantial in children with acute otitis media with perforation and chronic suppurative otitis media.

CONCLUSION

Disease prevention through good hygiene practices, breastfeeding, reducing smoke exposure, immunisation and limiting noise exposure is recommended. Children with acute otitis media with perforation, chronic suppurative otitis media, complications of otitis media, and significant hearing loss should be prioritised for medical treatment.

Sustained reduction in vaccine-type invasive pneumococcal disease despite waning effects of a catch-up campaign in Kilifi, Kenya: A mathematical model based on pre-vaccination data

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We predict a substantial decline in the carriage prevalence of vaccine serotypes.

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About a 56% reduction in invasive pneumococcal disease is also predicted.

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The decline is predicted to be sustainable ten years post-vaccination.

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The current vaccination schedule is unlikely to achieve elimination of vaccine serotypes.

Background

In 2011, Kenya introduced the 10-valent pneumococcal conjugate vaccine together with a catch-up campaign for children aged <5 years in Kilifi County. In a post-vaccination surveillance study based in Kilifi, there was a substantial decline in invasive pneumococcal disease (IPD). However, given the continued circulation of the vaccine serotypes it is possible that vaccine-serotype disease may re-emerge once the effects of the catch-up campaign wear off.

Methods

We developed a compartmental, age-structured dynamic model of pneumococcal carriage and invasive disease for three serotype groups: the 10-valent vaccine serotypes and two groups of non-vaccine serotypes based on their susceptibility to mutual competition. The model was calibrated to age- and serotype-specific data on carriage and IPD in the pre-vaccination era and used to predict carriage prevalence and IPD up to ten years post-vaccination in Kilifi. The model was validated against the observed carriage prevalence after vaccine introduction.

Results

The model predicts a sustained reduction in vaccine-type pneumococcal carriage prevalence from 33% to 8% in infants and from 30% to 8% in 1–5 year olds over the 10-year period following vaccine introduction. The incidence of IPD is predicted to decline across all age groups resulting in an overall reduction of 56% in the population, corresponding to 10.4 cases per 100,000 per year. The vaccine-type IPD incidence is estimated to decline by 83% while non-vaccine-type IPD incidence is predicted to increase by 52%. The model's predictions of carriage prevalence agrees well with the observed data in the first five years post-vaccination.

Conclusion

We predict a sustained and substantial decline in IPD through PCV vaccination and that the current regimen is insufficient to fully eliminate vaccine-serotype circulation in the model. We show that the observed impact is likely to be sustained despite waning effects of the catch-up campaign.

Limited impact of neonatal or early infant schedules of 7-valent pneumococcal conjugate vaccination on nasopharyngeal carriage of Streptococcus pneumoniae in Papua New Guinean children: A randomized controlled trial

Streptococcus pneumoniae is a leading cause of pneumonia, the most common cause of childhood death. Papua New Guinean children experience high rates of nasopharyngeal pneumococcal colonization within weeks of birth, predisposing them to pneumococcal disease. In a trial to determine the safety and immunogenicity of early infant vaccination with 7-valent pneumococcal conjugate vaccine (7vPCV), we investigated the impact of early schedules on pneumococcal carriage. Infants were randomized at birth to receive 7vPCV in a 0-1-2-month (n = 101) or a 1-2-3-month (n = 105) schedule or no 7vPCV (n = 106). All children received 23-valent pneumococcal polysaccharide vaccine at age 9 months. We cultured nasopharyngeal swabs (NPS) collected at ages 1, 2, 3, 4 weeks and 3, 9, 18 months, and middle ear discharge if present. Pneumococcal serotypes were identified by the Quellung reaction. A total of 1761 NPS were cultured. The prevalence of pneumococcal carriage was 22% at 1 week of age, rising to 80% by age 3 months and remained >70% thereafter, with high-density carriage in 42% of pneumococcus-positive samples. We identified 63 different serotypes; 43% of isolates from controls were 13vPCV serotypes. There were no significant differences in 7vPCV serotype carriage between 7vPCV recipients and controls at any age (22% vs. 31% at 9 months, p = 0.2). At age 9 months the prevalence of non-7vPCV carriage was 17% higher in 7vPCV recipients (48%) than in controls (25%, p = 0.02). More non-7vPCV serotypes were isolated from ear discharge in 16 7vPCV recipients than from 4 controls (48% vs. 25%, p = 0.13). The limited impact of neonatal or accelerated infant 7vPCV schedules on vaccine serotype carriage is probably due to the early onset of dense carriage of a broad range of pneumococcal serotypes. While serotype-independent pneumococcal vaccines are needed in high-risk populations, the underlying environmental factors and sources of infection must be investigated. http://clinicaltrials.gov/ct2/show/NCT00219401.

A longitudinal study of natural antibody development to pneumococcal surface protein A families 1 and 2 in Papua New Guinean Highland children: a cohort study

BACKGROUND

Pneumococcal surface protein A (PspA), a conserved virulence factor essential for Streptococcus pneumoniae attachment to upper respiratory tract (URT) epithelia, is a potential vaccine candidate for preventing colonisation.

METHODS

This cohort study was conducted in the Asaro Valley in the Eastern Highlands Province of Papua New Guinea, of which Goroka town is the provincial capital. The children included in the analysis were participants in a neonatal pneumococcal conjugate vaccine trial (ClinicalTrials.gov NCT00219401) that was conducted between 2005 and 2009. We investigated the development of anti-PspA antibodies in the first 18 months of life relative to URT pneumococcal carriage in Papua New Guinean infants who experience one of the earliest and highest colonisation rates in the world. Blood samples and nasopharyngeal swabs were collected from a cohort of 88 children at ages 3, 9, and 18 months to quantify immunoglobulin G (IgG) levels to PspA families 1 and 2 using an enzyme-linked immunosorbent assay and to determine URT carriage.

RESULTS

Seventy-three per cent (64/88) of infants carried S. pneumoniae at age 3 months; 85 % (75/88) at 9 months, and 83 % (73/88) at 18 months. PspA-IgG levels declined between ages 3 and 9 months (p < 0.001), then increased between 9 and 18 months (p < 0.001). At age 3 months, pneumococcal carriers showed lower PspA1-IgG levels (geometric mean concentration [GMC] 602 arbitrary units [AU]/ml, 95 % confidence interval [CI] 497-728) than non-carriers (GMC 1058 AU/ml [95 % CI 732-1530]; p = 0.008), while at 9 months, PspA1- and PspA2-IgG levels were significantly higher in carriers (PspA1: 186 AU/ml, 95 % CI 136-256; PspA2: 284 AU/ml, 95 % CI 192-421) than in non-carriers (PspA1 87 AU/ml, 95 % CI 45-169; PspA2 74 AU/ml, 95 % CI 34-159) (PspA1: p = 0.037, PspA2: p = 0.003).

CONCLUSION

Our findings confirm that PspA is immunogenic and indicate that natural anti-PspA immune responses are acquired through exposure and develop with age. PspA may be a useful candidate in an infant pneumococcal vaccine to prevent early URT colonisation.

Reflections on pneumonia in the tropics

This review of pneumonia in the tropics is based on experience with respiratory infectons in Papua New Guinea since the 1970s. It discusses ideas, principles, historical aspects of pneumonia research and the need to work with people in the community. In order to understand pneumonia in a tropical setng and evaluate new interventons it is essental to study the ecosystem of the causatve infectons, within the host and the community and between interactng microorganisms. Vaccines are much-needed preventve tools, and for pneumonia in a highly endemic setng the preventon of severe and fatal disease takes priority over the preventon of infecton. In this setng mild infecton plays an important role in preventng severe disease. For achieving long-term sustainable outcomes, sometmes ‘less is more’. A multpronged approach is required to control and prevent pneumonia, and in devising new ways of doing so. This includes appropriate and accessible clinical care, a clean, smoke-free environment, good nutriton and a range of vaccines. Also required are persistent advocacy from the global scientfc community and strong engagement with and by the communites that bear the burden of disease. Beter health care must be pursued in conjuncton with raising literacy rates and reducing poverty.

The role of influenza and parainfluenza infections in nasopharyngeal pneumococcal acquisition among young children

BACKGROUND

Animal models suggest that influenza infection favors nasopharyngeal acquisition of pneumococci. We assessed this relationship with influenza and other respiratory viruses in young children.

METHODS

A case-control study was nested within a prospective cohort study of acute respiratory illness (ARI) in Andean children <3 years of age (RESPIRA-PERU study). Weekly household visits were made to identify ARI and obtain nasal swabs for viral detection using real-time reverse-transcription polymerase chain reaction. Monthly nasopharyngeal (NP) samples were obtained to assess pneumococcal colonization. We determined whether specific respiratory viral ARI episodes occurring within the interval between NP samples increased the risk of NP acquisition of new pneumococcal serotypes.

RESULTS

A total of 729 children contributed 2128 episodes of observation, including 681 pneumococcal acquisition episodes (new serotype, not detected in prior sample), 1029 nonacquisition episodes (no colonization or persistent colonization with the same serotype as the prior sample), and 418 indeterminate episodes. The risk of pneumococcal acquisition increased following influenza-ARI (adjusted odds ratio [AOR], 2.19; 95% confidence interval [CI], 1.02-4.69) and parainfluenza-ARI (AOR, 1.86; 95% CI, 1.15-3.01), when compared with episodes without ARI. Other viral infections (respiratory syncytial virus, human metapneumovirus, human rhinovirus, and adenovirus) were not associated with acquisition.

CONCLUSIONS

Influenza and parainfluenza ARIs appeared to facilitate pneumococcal acquisition among young children. As acquisition increases the risk of pneumococcal diseases, these observations are pivotal in our attempts to prevent pneumococcal disease.

Nasopharyngeal microbial interactions in the era of pneumococcal conjugate vaccination

The nasopharynx of children is often colonised by microorganisms such as Streptococcus pneumoniae (the pneumococcus) that can cause infections including pneumonia and otitis media. In this complex environment, bacteria and viruses may impact each other through antagonistic as well as synergistic interactions. Vaccination may alter colonisation dynamics, evidenced by the rise in non-vaccine serotypes following pneumococcal conjugate vaccination. Discovery of an inverse relationship between S. pneumoniae and Staphylococcus aureus carriage generated concern that pneumococcal vaccination could increase S. aureus carriage and disease. Here we review data on co-colonisation of pathogens in the nasopharynx, focusing on S. pneumoniae and the impact of pneumococcal vaccination. Thus far, pneumococcal vaccination has not had a sustained impact on S. aureus carriage but it is associated with an increase in non-typeable Haemophilus influenzae in acute otitis media aetiology. Advances in bacterial and viral detection methodologies have facilitated research in nasopharyngeal microbiology and will aid investigation of potential vaccine-induced changes, particularly when baseline studies can be conducted prior to pneumococcal vaccine introduction.

The fundamental link between pneumococcal carriage and disease

Streptococcus pneumoniae (pneumococcus) is a major cause of worldwide mortality and morbidity, and to a large extent is vaccine-preventable. Nasopharyngeal carriage of pneumococcus precedes disease and is the source of pneumococcal spread between people. The use of vaccine effect on carriage as part of the vaccine licensure and post-vaccine introduction evaluation could facilitate and expand the licensure of new, life-saving pneumococcal vaccines and enable a comprehensive estimate of population effects after vaccine introduction. The authors provide a review of the evidence supporting pneumococcal carriage at the individual level as an immediate and necessary precursor to pneumococcal disease. Based on such a causal link between carriage and disease, the authors emphasize the role of information on pneumococcal carriage in vaccine trials and in public health decision-making.

Rates of acquisition and clearance of pneumococcal serotypes in the nasopharynges of children in Kilifi District, Kenya

Background. To understand and model the impact of pneumococcal conjugate vaccines at the population level, we need to know the transmission dynamics of individual pneumococcal serotypes. We estimated serotype-specific clearance and acquisition rates of nasopharyngeal colonization among Kenyan children.

Methods. Children aged 3–59 months who were identified as carriers in a cross-sectional survey were followed-up approximately 1, 2, 4, 8, 16, and 32 days later and monthly thereafter until culture of 2 consecutive swabs yielded an alternative serotype or no pneumococcus. Serotype-specific clearance rates were estimated by exponential regression of interval-censored carriage durations. Duration was estimated as the reciprocal of the clearance rate, and acquisition rates were estimated on the basis of prevalence and duration, assuming an equilibrium state.

Results. Of 2840 children sampled between October 2006 and December 2008, 1868 were carriers. The clearance rate was 0.032 episodes/day (95% confidence interval [CI], .030–.034), for a carriage duration of 31.3 days, and the rate varied by serotype (P < .0005). Carriage durations for the 28 serotypes with ≥10 carriers ranged from 6.7 to 50 days. Clearance rates increased with year of age, adjusted for serotype (hazard ratio, 1.21; 95% CI, 1.15–1.27). The acquisition rate was 0.061 episodes/day (95% CI, .055–.067), which did not vary with age. Serotype-specific acquisition rates varied from 0.0002 to 0.0022 episodes/day. Serotype-specific acquisition rates correlated with prevalence (r = 0.91; P < .00005) and with acquisition rates measured in a separate study involving 1404 newborns in Kilifi (r = 0.87; P < .00005).

Conclusions. The large sample size and short swabbing intervals provide a precise description of the prevalence, duration, and acquisition of carriage of 28 pneumococcal serotypes. In Kilifi, young children experience approximately 8 episodes of carriage per year. The declining prevalence with age is attributable to increasing clearance rates.

Pneumococcal carriage at age 2 months is associated with growth deficits at age 6 months among infants in South India

Nasopharyngeal colonization is the first step in the pathway to Streptococcus pneumoniae (Spn) infection, a leading cause of childhood morbidity and mortality. We investigated the effect of Spn colonization at ages 2 and 4 mo on growth at age 6 mo among 389 infants living in rural South India by using data from an Spn carriage study nested within a randomized, double-blind, placebo-controlled community trial designed to evaluate the impact of newborn vitamin A supplementation on Spn carriage in the first 6 mo of life. Primary outcomes were weight, length, and anthropometric indices of nutritional status. Growth data at age 6 mo were available for 84% (389 of 464) of infants in the Spn carriage study. Carriage at age 2 mo was associated with increased odds of stunting [OR: 3.07 (95% CI: 1.29, 7.36) P = 0.012] and lower weight [β: -266 g (95% CI: -527, -5) P = 0.045], length [β: -1.31 cm (95% CI: -2.32, -0.31) P = 0.010], and length-for-age Z scores [β: -0.59; (95% CI: -1.05, -0.13) P = 0.012] at age 6 mo. Spn carriage at age 4 mo did not affect growth. Carriage of invasive serotypes at age 2 mo was associated with decreases in mean weight [β: -289 g; (95% CI: -491, -106) P = 0.002] and length [β:-0.38 cm (95% CI: -1.49, -0.01) P = 0.047] at age 6 mo. Newborn vitamin A supplementation did not modify the association between Spn carriage and growth. Results suggest that pneumococcal carriage at age 2 mo is an independent risk factor for poor growth in young infants. Future studies need to clarify the role of Spn carriage on growth retardation in low-income countries.

Rates of acquisition of pneumococcal colonization and transmission probabilities, by serotype, among newborn infants in Kilifi District, Kenya

This study determined the serotype-specific acquisition rates for pneumococcal colonization in a cohort of 1404 newborn infants followed intensively for 3 months. By observing pneumococcal carriage in family members, we were able to determine serotype-specific transmission probabilities between relatives.

Background. Herd protection and serotype replacement disease following introduction of pneumococcal conjugate vaccine (PCV) are attributable to the vaccine's impact on colonization. Prior to vaccine introduction in Kenya, we did an epidemiological study to estimate the rate of pneumococcal acquisition, by serotype, in an uncolonized population.

Methods. Nasopharyngeal swab specimens were taken from newborns aged ≤7 days and weekly thereafter for 13 weeks. Parents, and siblings aged <10 years, were swabbed at monthly intervals. Swabs were transported in skim milk-tryptone-glucose-glycerin and cultured on gentamicin blood agar. Pneumococci were serotyped by the Quellung reaction. We used survival analysis and Cox regression analysis to examine serotype-specific acquisition rates and risk factors and calculated transmission probabilities from the pattern of acquisitions within the family.

Results. Of 1404 infants recruited, 887 were colonized by 3 months of age, with the earliest acquisition detected on the first day of life. The median time to acquisition was 38.5 days. The pneumococcal acquisition rate was 0.0189 acquisitions/day (95% confidence interval, .0177–.0202 acquisitions/day). Serotype-specific acquisition rates varied from 0.00002–0.0025 acquisitions/day among 49 different serotypes. Season, coryza, and exposure to cigarettes, cooking fumes, and other children in the home were each significant risk factors for acquisition. The transmission probability per 30-day duration of contact with a carrier was 0.23 (95% CI, .20–.26).

Conclusions. Newborn infants in Kilifi have high rates of nasopharyngeal acquisition of pneumococci. Half of these acquisitions involve serotypes not included in any current vaccine. Several risk factors are modifiable through intervention. Newborns represent a consistent population of pneumococcus-naive individuals in which to estimate the impact of PCV on transmission.

Characterization of Th17 responses to Streptococcus pneumoniae in humans: comparisons between adults and children in a developed and a developing country

Intranasal exposure to Streptococcus pneumoniae as well as mucosal or parenteral immunization with a recently developed killed pneumococcal whole cell vaccine, confer Th17-mediated protection against subsequent S. pneumoniae colonization in mice. Given our interest in the function of Th17 cells and the ongoing efforts to develop this vaccine for use in infants and children in developing countries, we analyzed Th17 responses to the whole cell antigen (WCA) and individual pneumococcal antigens in healthy individuals and patients with pneumococcal disease and compared responses in children and adults from Sweden and Bangladesh. Peripheral blood mononuclear cells (PBMCs) isolated from Swedish adults produced IL-17A after stimulation with WCA, with the pneumolysoid PdT and with the protein required for cell separation in group B streptococci (PcsB). IL-22 and IFN-γ responses were also detected, but these cytokines originated from separate CD4+ T cell subsets. PBMCs from Swedish children produced lower levels of IL-17A in response to WCA compared to adults, whereas no such difference was noted from the samples from Bangladesh, where responses by children and adults were both significantly higher than those in Sweden. High IL-17A responses to stimulation with WCA were also observed in children with proven or probable pneumococcal pneumonia. Our results thus demonstrate the presence of Th17-type T cells that are specific for pneumococcus in both children and adults. The different levels of Th17 responses to pneumococci in children and adults in developing and developed countries, which may at least partly be due to differences in exposure to pneumococci, are important factors to consider in the evaluation of candidate pneumococcal protein-based vaccines in human trials.

Decrease in pneumococcal co-colonization following vaccination with the seven-valent pneumococcal conjugate vaccine

Understanding the epidemiology of pneumococcal co-colonization is important for monitoring vaccine effectiveness and the occurrence of horizontal gene transfer between pneumococcal strains. In this study we aimed to evaluate the impact of the seven-valent pneumococcal conjugate vaccine (PCV7) on pneumococcal co-colonization among Portuguese children. Nasopharyngeal samples from children up to 6 years old yielding a pneumococcal culture were clustered into three groups: pre-vaccine era (n = 173), unvaccinated children of the vaccine era (n = 169), and fully vaccinated children (4 doses; n = 150). Co-colonization, serotype identification, and relative serotype abundance were detected by analysis of DNA of the total bacterial growth of the primary culture plate using the plyNCR-RFLP method and a molecular serotyping microarray-based strategy. The plyNCR-RFLP method detected an overall co-colonization rate of 20.1%. Microarray analysis confirmed the plyNCR-RFLP results. Vaccination status was the only factor found to be significantly associated with co-colonization: co-colonization rates were significantly lower (p = 0.004; Fisher's exact test) among fully vaccinated children (8.0%) than among children from the pre-PCV7 era (17.3%) or unvaccinated children of the PCV7 era (18.3%). In the PCV7 era there were significantly less non-vaccine type (NVT) co-colonization events than would be expected based on the NVT distribution observed in the pre-PCV7 era (p = 0.024). In conclusion, vaccination with PCV7 resulted in a lower co-colonization rate due to an asymmetric distribution between NVTs found in single and co-colonized samples. We propose that some NVTs prevalent in the PCV7 era are more competitive than others, hampering their co-existence in the same niche. This result may have important implications since a decrease in co-colonization events is expected to translate in decreased opportunities for horizontal gene transfer, hindering pneumococcal evolution events such as acquisition of antibiotic resistance determinants or capsular switch. This might represent a novel potential benefit of conjugate vaccines.

Effect of pneumococcal vaccination on nasopharyngeal carriage of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus in Fijian children

The 7-valent pneumococcal conjugate vaccine (PCV7) reduces carriage of vaccine type Streptococcus pneumoniae but leads to replacement by nonvaccine serotypes and may affect carriage of other respiratory pathogens. We investigated nasopharyngeal carriage of S. pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus in Fijian infants participating in a pneumococcal vaccine trial using quantitative PCR. Vaccination did not affect pathogen carriage rates or densities, whereas significant differences between the two major ethnic groups were observed.

The continuing role of Haemophilus influenzae type b carriage surveillance as a mechanism for early detection of invasive disease activity

Prior to the introduction of Haemophilus influenzae type b (Hib) conjugate vaccines, Hib was the leading cause of bacterial meningitis in children under five years of age worldwide. In countries that have adopted Hib vaccination schedules, invasive disease has reduced markedly. Oro-naso pharyngeal carriage is recognized as the most significant source of infection. Hib carriage is significantly associated with poverty, such as overcrowding, poor ventilation in houses, lack of running water, and high smoking rates. Additionally, many Indigenous minority groups report high rates of Hib carriage. A resurgence of Hib disease among Alaskan children in the 1990s, lead to a change in approach to eliminate Hib disease and carriage in high-risk populations. This new approach identifies strategies for eliminating Hib disease focusing on the reservoirs of colonization within families and communities. Monitoring Hib carriage continues to offer an early warning system, whereby intervention could prevent invasive disease resurgence.

Multilocus sequence typing of Streptococcus pneumoniae by use of mass spectrometry

Multilocus sequence typing (MLST) is an important tool for the global surveillance of bacterial pathogens that is performed by comparing the sequences of designated housekeeping genes. We developed and tested a novel mass spectrometry-based method for MLST of Streptococcus pneumoniae. PCR amplicons were subjected to in vitro transcription and base-specific cleavage, followed by analysis of the resultant fragments by using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Comparison of the cleavage fragment peak patterns to a reference sequence set permitted automated identification of alleles. Validation experiments using 29 isolates of S. pneumoniae revealed that the results of MALDI-TOF MS MLST matched those obtained by traditional sequence-based MLST for 99% of alleles and that the MALDI-TOF MS method accurately identified two single-nucleotide variations. The MADLI-TOF MS method was then used for MLST analysis of 43 S. pneumoniae isolates from Papua New Guinean children. The majority of the isolates present in this population were not clonal and contained seven new alleles and 30 previously unreported sequence types.

Early acquisition and high nasopharyngeal co-colonisation by Streptococcus pneumoniae and three respiratory pathogens amongst Gambian new-borns and infants

Background

Although Haemophilus influenzae type b (Hib), Staphylococcus aureus and Moraxella catarrhalis are important causes of invasive and mucosal bacterial disease among children, co-carriage with Streptococcus pneumoniae during infancy has not been determined in West Africa.

Methods

Species specific PCR was applied to detect each microbe using purified genomic DNA from 498 nasopharyngeal (NP) swabs collected from 30 Gambian neonates every two weeks from 0 to 6 months and bi-monthly up to 12 months.

Results

All infants carried S. pneumoniae, H. influenzae and M. catarrhalis at several time points during infancy. S.pneumoniae co-colonized the infant nasopharynx with at least one other pathogen nine out of ten times. There was early colonization of the newborns and neonates, the average times to first detection were 5, 7, 3 and 14 weeks for S. pneumoniae, H. influenzae, M. catarrhalis and S. aureus respectively. The prevalence of S. pneumoniae, H. influenzae and M. catarrhalis increased among the neonates and exceeded 80% by 13, 15 and 23 weeks respectively. In contrast, the prevalence of S. aureus decreased from 50% among the newborns to 20% amongst nine-week old neonates. S. pneumoniae appeared to have a strong positive association with H. influenzae (OR 5.03; 95% CI 3.02, 8.39; p < 0.01) and M. catarrhalis (OR 2.20; 95% CI 1.29; p < 0.01) but it was negatively associated with S. aureus (OR 0.53; 95% CI 0.30, 0.94; p = 0.03).

Conclusion

This study shows early acquisition and high co-carriage of three important respiratory pathogens with S. pneumoniae in the nasopharyngeal mucosa among Gambian neonates and infants. This has important potential implications for the aetiology of respiratory polymicrobial infections, biofilm formation and vaccine strategies.

Family and community concerns about post-mortem needle biopsies in a Muslim society

Background

Post-mortem needle biopsies have been used in resource-poor settings to determine cause of death and there is interest in using them in Bangladesh. However, we did not know how families and communities would perceive this procedure or how they would decide whether or not to consent to a post-mortem needle biopsy. The goal of this study was to better understand family and community concerns and decision-making about post-mortem needle biopsies in this low-income, predominantly Muslim country in order to design an informed consent process.

Methods

We conducted 16 group discussions with family members of persons who died during an outbreak of Nipah virus illness during 2004-2008 and 11 key informant interviews with their community and religious leaders. Qualitative researchers first described the post-mortem needle biopsy procedure and asked participants whether they would have agreed to this procedure during the outbreak. Researchers probed participants about the circumstances under which the procedure would be acceptable, if any, their concerns about the procedure, and how they would decide whether or not to consent to the procedure.

Results

Overall, most participants agreed that post-mortem needle biopsies would be acceptable in some situations, particularly if they benefitted society. This procedure was deemed more acceptable than full autopsy because it would not require major delays in burial or remove organs, and did not require cutting or stitching of the body. It could be performed before the ritual bathing of the body in either the community or hospital setting. However, before consent would be granted for such a procedure, the research team must gain the trust of the family and community which could be difficult. Although consent may only be provided by the guardians of the body, decisions about consent for the procedure would involve extended family and community and religious leaders.

Conclusions

The possible acceptability of this procedure during outbreaks represents an important opportunity to better characterize cause of death in Bangladesh which could lead to improved public health interventions to prevent these deaths. Obstacles for research teams will include engaging all major stakeholders in decision-making and quickly building a trusting relationship with the family and community, which will be difficult given the short window of time prior to the ritual bathing of the body.

Between-strain competition in acquisition and clearance of pneumococcal carriage--epidemiologic evidence from a longitudinal study of day-care children

The state of pneumococcal carriage-that is, pneumococcal colonization in the nasopharynx of healthy persons-represents a reservoir for the spread of pneumococci among individuals. In light of the introduction of new pneumococcal conjugate vaccines, further knowledge on the dynamics of pneumococcal carriage is important. Different serotypes (strains) of pneumococcus are known to compete with each other in colonizing human hosts. Understanding the strength and mode of between-serotype competition is important because of its implications for vaccine-induced changes in the ecology of pneumococcal carriage. Competition may work through reduced acquisition of new serotypes, due to concurrent carriage in the individual, or through enhanced clearance of serotypes in carriers who harbor more than 1 serotype simultaneously. The authors employed longitudinal data (1999-2001) on pneumococcal carriage in Danish day-care children to analyze between-serotype competition. The data included observations of carriage in children who had not been vaccinated against pneumococcus, and the level of pneumococcal antibiotic resistance and antibiotic usage in the community was very low. Clearance of any single serotype was not affected by simultaneous carriage of other serotypes. In contrast, acquisition of other serotypes in already-colonized hosts was weak (relative rate of acquisition = 0.09, 95% credible interval: 0.05, 0.15).

Maternal antibodies to pneumolysin but not to pneumococcal surface protein A delay early pneumococcal carriage in high-risk Papua New Guinean infants

Immunization of pregnant women can be an efficient strategy to induce early protection in infants in developing countries. Pneumococcal protein-based vaccines may have the capacity to induce pneumococcal serotype-independent protection. To understand the potential of maternal pneumococcal protein-specific antibodies in infants in high-risk areas, we studied the placental transfer of naturally acquired antibodies to pneumolysin (Ply) and pneumococcal surface protein A family 1 and 2 (PspA1 and PspA2) in relation to onset of pneumococcal nasopharyngeal carriage in infants in Papua New Guinea (PNG). In this study, 76% of the infants carried Streptococcus pneumoniae in the upper respiratory tract within the first month of life, at a median age of 19 days. Maternal and cord blood antibody titers to Ply (rho = 0.824, P < 0.001), PspA1 (rho = 0.746, P < 0.001), and PspA2 (rho = 0.631, P < 0.001) were strongly correlated. Maternal pneumococcal carriage (hazard ratio [HR], 2.60; 95% confidence interval [CI], 1.25 to 5.39) and younger maternal age (HR, 0.74; 95% CI, 0.54 to 1.00) were independent risk factors for early carriage, while higher cord Ply-specific antibody titers predicted a significantly delayed onset (HR, 0.71; 95% CI, 0.52 to 1.00) and cord PspA1-specific antibodies a significantly younger onset of carriage in PNG infants (HR, 1.57; 95% CI, 1.03 to 2.40). Maternal vaccination with a pneumococcal protein-based vaccine should be considered as a strategy to protect high-risk infants against pneumococcal disease by reducing carriage risks in both mothers and infants.

Nasopharyngeal carriage of Streptococcus pneumoniae in Navajo and White Mountain Apache children before the introduction of pneumococcal conjugate vaccine

BACKGROUND

Infants and children are frequently colonized with pneumococcus. Recent nasopharyngeal acquisition of pneumococcus is thought to precede disease episodes. The increased risk of pneumococcal disease among Navajo and White Mountain Apache populations has been documented. Little is known about the dynamics of pneumococcal carriage in these populations.

METHODS

A group randomized, controlled trial of 7-valent conjugate pneumococcal vaccine (PnCRM7, Wyeth) was conducted on the Navajo and Apache reservations. A nasopharyngeal (NP) carriage study was nested in the trial to evaluate the impact of PnCRM7 on carriage. Children <6 years of age had NP swabs collected at enrollment and at 6 and 12 months following enrollment. We analyzed carriage data from children in control vaccine randomized communities to describe the epidemiology of pneumococcal carriage.

RESULTS

Of the 410 participants enrolled, 92% were colonized with pneumococcus at least once during the course of the study. Sixty-three percent of NP specimens were positive for pneumococcus. The most common serotypes were 6A, 6B, nontypable, 23F, 14, 19F, 19A, and 9V. Thirty-eight percent of isolates were vaccine serotypes. Age <2 years, male sex, daycare attendance, and having a sibling colonized with pneumococcus were associated with an increased risk of carriage.

CONCLUSIONS

The high carriage prevalence among Navajo and Apache children reflects an intense exposure to pneumococcus. The lack of modifiable risk factors for carriage highlights the importance of preventive strategies for disease control.

Nasopharyngeal carriage of S. pneumoniae among young children in rural Nepal

OBJECTIVES

To provide epidemiologic data on Streptococcus pneumoniae (Spn) carriage in Nepal.

METHODS

Prospective, population-based study among children in Sarlahi, Nepal to estimate carriage prevalence, identify risk factors, and determine antibiotic susceptibility patterns and serotype distribution. Between December 2003 and July 2004, NP specimens were collected from 604 children aged 1-36 months with acute lower respiratory infection (ALRI) and 604 healthy, age- and season-matched controls.

RESULTS

Of the 1100 specimens analysed, carriage prevalence was approximately 80% in both groups. In the multivariate analyses, significant risk factors for Spn carriage in controls were Muslim religion [adjusted odds ratio (AOR): 2.93] and no latrine in the household (AOR: 2.41). Those treated for a recent illness had lower carriage rates (AOR: 0.37). Results were similar for ALRI cases with the addition of age >or=12 months (AOR: 1.68), and symptomatic infection (AOR: 3.78) as risk factors. The antibiotics and proportions of isolates resistant to them were as follows: penicillin 4.5%, cotrimoxazole 89.2%, chloramphenicol 1.4%, erythromycin 1.5% and tetracycline 22.7%. The most prevalent serogroups/types were 6, 19, 23, 15, 9 and 10.

CONCLUSIONS

Young children in rural Nepal experience high rates of Spn carriage. Most isolates were resistant to cotrimoxazole. Current conjugate Spn vaccines may substantially reduce the risk of a severe pneumonia and other Spn infections.

Multiplex PCR reveals a high rate of nasopharyngeal pneumococcal 7-valent conjugate vaccine serotypes co-colonizing indigenous Warao children in Venezuela

Knowledge of co-colonization with multiple pneumococcal serotypes is becoming very important in the light of both serotype replacement and switching as a result of vaccination. Co-colonization has been reported to occur in up to 30 % of carriers, especially in populations with high Streptococcus pneumoniae carriage rates. For the determination of co-colonization, single colonies of nasopharyngeal specimens are serotyped with the Quellung method, a costly method with a low sensitivity. Here we explore the use of a multiplex PCR to identify simultaneous carriage of the capsular serotypes targeted by the 7-valent conjugate vaccine. We applied this multiplex PCR to 50 primary cultures from the nasopharyngeal swabs of healthy Warao Amerindian children, a population with a high pneumococcal carriage rate, most of them with vaccine serotypes, and we identified a second serotype in 20 % (n=10) of the pneumococci carriers. These results were confirmed by detailed serotyping of multiple colonies isolated from the primary culture with the Quellung method. We conclude that the multiplex PCR is a sensitive, simple and cost-effective method for detecting multiple serotypes in nasopharyngeal cultures, and thus might be useful for the monitoring of pneumococcal colonization over time, especially in the surveillance of nasopharyngeal colonization after conjugate vaccination.

The impact of vaccines on pneumonia: key lessons from Haemophilus influenzae type b conjugate vaccines

This article explores key lessons learned from vaccination with Haemophilus influenzae type b (Hib) conjugate vaccine and how these lessons may provide insight into the impact of emergent pneumococcal vaccines against pneumonia. The worldwide value of Hib vaccination for reducing Hib disease burden and carriage is reviewed. Using comparisons of data for pneumococcus versus Hib, the article concludes that epidemiological and biological differences between these pathogens will complicate efforts to use results from the Hib vaccine experience to predict outcomes following pneumococcal conjugate vaccine introduction.

WITHDRAWN: Antibiotics for persistent nasal discharge (rhinosinusitis) in children

BACKGROUND

Nasal discharge (rhinosinusitis) is extremely common in children. It is the result of inflammation of the mucosa of the upper respiratory tract, and is usually due to either infection or allergy. Infections may be caused by bacteria.

OBJECTIVES

To determine the effectiveness of antibiotics versus placebo or standard therapy in treating children with persistent nasal discharge (rhinosinusitis) for at least 10 days.

SEARCH STRATEGY

In this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2005) which includes the ARI Group's specialised trials register; MEDLINE (1966 to April Week 3, 2005) EMBASE (1997 to December 2004), and the references of relevant articles were searched. Authors and pharmaceutical companies were contacted.

SELECTION CRITERIA

All randomised controlled trials that compared antibiotics versus placebo or standard therapy. Trials which included the use of other medications were included if all participants were allowed equal access to such medications or if the additional or alternative therapies were regarded as ineffective. Trials that only combined or compared antibiotics with surgery, or sinus puncture and lavage, were not included in the review.

DATA COLLECTION AND ANALYSIS

Data were extracted by a single author for the following eight outcomes: overall clinical failure (primary outcome), failure to cure, failure to improve, clinical improvement, time to resolution, complications, side-effects and bacteriologic failure. For the dichotomous outcome variables of each individual study, proportional and absolute risk reductions were calculated using a modified intention-to-treat analysis. The summary weighted risk ratio and 95% confidence interval (CI) (fixed effect model) were calculated using the inverse of the variance of each study result for weighting (Cochrane statistical package, RevMan version 4.2).

MAIN RESULTS

A total of six studies involving 562 children compared antibiotics with placebo or standard therapy. All studies were randomised but most were still susceptible to bias. Five of the studies were conducted in emergency, allergy or ENT clinics. Four of the studies required children to have x-ray changes consistent with sinusitis. Only the primary outcome (overall clinical failure) was reported in all studies. Around 40% of all randomised children did not have a clinical success documented when reviewed two to six weeks after randomisation. The control event rate varied from to 22 to 71% (mean 46%). The risk ratio estimated using a fixed effects model was 0.75 (95% CI 0.61 to 0.92). There was no evidence of statistical heterogeneity. Side effects (sufficient to cease treatment) occurred in 4 of 189 control group children (four studies). More children treated with antibiotics had side effects (17 of 330), but this difference was not statistically significant (RR 1.75, 95% CI 0.63 to 4.82).

AUTHORS' CONCLUSIONS

For children with persistent nasal discharge or older children with radiographically confirmed sinusitis, the available evidence suggests that antibiotics will reduce the probability of persistence in the short to medium-term. The benefits appear to be modest and around eight children must be treated in order to achieve one additional cure (number needed to treat (NNT) 8, 95% CI 5 to 29). No long term benefits have been documented. These conclusions are based on a small number of small randomised controlled trials and may require revision as additional data become available.

Nasopharyngeal carriage of Streptococcus pneumoniae in Gambian infants: a longitudinal study

BACKGROUND

To prepare for national introduction of a pneumococcal conjugate vaccine of restricted valency, we studied nasopharyngeal carriage of Streptococcus pneumoniae in Gambian infants.

METHODS

We studied 236 infants in 21 villages. We collected nasopharyngeal swab samples at birth, twice per month for 6 months, and every second month until 1 year of age. We studied time to acquisition and duration of pneumococcal carriage according to serotype.

RESULTS

All infants carried S. pneumoniae at some point. Sixty-five serotypes were found, and the 5 most common serotypes (6B, 19F, 6A, 14, and 23F) accounted for 51% of isolates. The mean age at first acquisition of carriage was 33 days (95% confidence interval, 29-36 days). There were no significant differences in acquisition rates between the 6 most common serotypes (P = .067) or between vaccine serotypes, vaccine-related serotypes, or nonvaccine serotypes (P = .317). However, the duration of carriage differed significantly between the 6 most common serotypes (P = .004). The rate of reacquisition of carriage and the duration of carriage did not differ significantly between the 6 most common serotypes (P = .229 and P = .669 respectively). However, nonvaccine types were acquired faster (P = .004) and were carried for a shorter duration (P < .001) than were vaccine serotypes. A previous episode of serotype 14 carriage was associated with delayed reacquisition of this serotype (P = .005) and longer duration of carriage (P = .017).

CONCLUSIONS

The data provided in this study regarding time to acquisition and duration of pneumococcal carriage in Gambian infants provide an important baseline for evaluating the impact of the introduction of a pneumococcal conjugate vaccine in The Gambia and elsewhere in Africa.

High rates of transmission of and colonization by Streptococcus pneumoniae and Haemophilus influenzae within a day care center revealed in a longitudinal study

Day care centers (DCCs) are unique settings where young children are at increased risk for colonization by pneumococci and Haemophilus influenzae. Although point prevalence studies in DCCs are frequent, only a few longitudinal studies on the dynamics of colonization have been published. We conducted a 1-year longitudinal study with 11 sampling periods on nasopharyngeal carriage of pneumococci and H. influenzae among 47 children who attended a single DCC. All isolates were antibiotyped and genotyped by pulsed-field gel electrophoresis. Pneumococci were also serotyped. Of the 414 samples obtained, 61.4% contained pneumococci, and 87% contained H. influenzae. Only 8.3% of the samples were negative for both species. Twenty-one pneumococcal clones and 47 H. influenzae clones were identified. Introduction of clones occurred during all year. Ninety-eight percent and 96% of all pneumococcal and H. influenzae isolates, respectively, belonged to clones shared by more than one child. Children were sequentially colonized with up to six pneumococcal clones (mean, 3.6) and five serotypes and nine H. influenzae clones (mean, 7.1). Clones with increased capacity for transmission and/or prolonged colonization were identified in both species. These two fitness properties appeared to be independent. In conclusion, among DCC attendees, a high rate of acquisition and turnover of strains was observed, and all children were overwhelmingly colonized by clones shared with others. DCCs are units where permanent introduction of new clones occurs, and attendees, as a whole, provide a pool of hosts where the fittest clones find privileged opportunities to persist and expand.

WITHDRAWN: Antibiotics for persistent nasal discharge (rhinosinusitis) in children

BACKGROUND

Nasal discharge (rhinosinusitis) is extremely common in children. It is the result of inflammation of the mucosa of the upper respiratory tract, and is usually due to either infection or allergy. Infections may be caused by bacteria.

OBJECTIVES

To determine the effectiveness of antibiotics versus placebo or standard therapy in treating children with persistent nasal discharge (rhinosinusitis) for at least 10 days.

SEARCH STRATEGY

In this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2005) which includes the ARI Group's specialised trials register; MEDLINE (1966 to April Week 3, 2005) EMBASE (1997 to December 2004), and the references of relevant articles were searched. Authors and pharmaceutical companies were contacted.

SELECTION CRITERIA

All randomised controlled trials that compared antibiotics versus placebo or standard therapy. Trials which included the use of other medications were included if all participants were allowed equal access to such medications or if the additional or alternative therapies were regarded as ineffective. Trials that only combined or compared antibiotics with surgery, or sinus puncture and lavage, were not included in the review.

DATA COLLECTION AND ANALYSIS

Data were extracted by a single author for the following eight outcomes: overall clinical failure (primary outcome), failure to cure, failure to improve, clinical improvement, time to resolution, complications, side-effects and bacteriologic failure. For the dichotomous outcome variables of each individual study, proportional and absolute risk reductions were calculated using a modified intention-to-treat analysis. The summary weighted risk ratio and 95% confidence interval (CI) (fixed effect model) were calculated using the inverse of the variance of each study result for weighting (Cochrane statistical package, RevMan version 4.2).

MAIN RESULTS

A total of six studies involving 562 children compared antibiotics with placebo or standard therapy. All studies were randomised but most were still susceptible to bias. Five of the studies were conducted in emergency, allergy or ENT clinics. Four of the studies required children to have x-ray changes consistent with sinusitis. Only the primary outcome (overall clinical failure) was reported in all studies. Around 40% of all randomised children did not have a clinical success documented when reviewed two to six weeks after randomisation. The control event rate varied from to 22 to 71% (mean 46%). The risk ratio estimated using a fixed effects model was 0.75 (95% CI 0.61 to 0.92). There was no evidence of statistical heterogeneity. Side effects (sufficient to cease treatment) occurred in 4 of 189 control group children (four studies). More children treated with antibiotics had side effects (17 of 330), but this difference was not statistically significant (RR 1.75, 95% CI 0.63 to 4.82).

AUTHORS' CONCLUSIONS

For children with persistent nasal discharge or older children with radiographically confirmed sinusitis, the available evidence suggests that antibiotics will reduce the probability of persistence in the short to medium-term. The benefits appear to be modest and around eight children must be treated in order to achieve one additional cure (number needed to treat (NNT) 8, 95% CI 5 to 29). No long term benefits have been documented. These conclusions are based on a small number of small randomised controlled trials and may require revision as additional data become available.

The preventable burden of pneumococcal disease in the developing world

The efficacy of pneumococcal conjugate vaccines (PCV) and their remarkable success in operational use in North America challenge us to define the burden of pneumococcal disease and the likely benefits of PCV use in developing countries. Community-based incidence studies of invasive pneumococcal disease (IPD) and vaccine probe analyses of efficacy trials suggest there are approximately 814,000 pneumococcal deaths in children aged <5 years in developing countries each year and 1-4 million episodes of pneumococcal pneumonia in Africa alone. PCV will be effective where there is a demonstrable burden of IPD attributable to vaccine serotypes but herd protection and serotype replacement effects are unpredictable given existing knowledge of pneumococcal epidemiology in developing countries. Operational use of PCV in well-monitored settings is required to estimate these effects.

Comparison between nasal swabs and nasopharyngeal aspirates for, and effect of time in transit on, isolation of Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, and Moraxella catarrhalis

We assessed the impact of the use of nasal swabs or nasopharyngeal aspirates and the time from specimen collection to storage at -70 degrees C on bacterial isolation. Haemophilus influenzae was isolated significantly less often from swabs than from nasopharyngeal aspirates. Samples in transit for >3 days were half as likely to grow Streptococcus pneumoniae and H. influenzae as those in transit for < or =3 days. There was no statistically significant difference for either Moraxella catarrhalis or Staphylococcus aureus.

Upper respiratory tract bacterial carriage in Aboriginal and non-Aboriginal children in a semi-arid area of Western Australia

BACKGROUND

Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are associated with otitis media (OM). Indigenous children experience particularly high rates of OM. Few studies worldwide have described upper respiratory tract (URT) carriage in Indigenous and non-Indigenous children living in the same area.

AIM

The aim of this study was to describe URT bacterial carriage in Aboriginal and non-Aboriginal children in the Kalgoorlie-Boulder area, Western Australia, as part of an investigation into causal pathways to OM.

METHODS

Five hundred four and 1045 nasopharyngeal aspirates were collected from 100 Aboriginal and 180 non-Aboriginal children, respectively, followed from birth to age 2 years. Standard procedures were used to identify bacteria.

RESULTS

Overall carriage rates of S. pneumoniae, M. catarrhalis and H. influenzae in Aboriginal children were 49%, 50% and 41%, respectively, and 25%, 25% and 11% in non-Aboriginal children. By age 2 months S. pneumoniae and M. catarrhalis had been isolated from 37% and 36% of Aboriginal children and from 11% and 12% of non-Aboriginal children, respectively. From age 3 months onward, carriage rates in Aboriginal children were 51% to 67% for S. pneumoniae and M. catarrhalis and 42% to 62% for H. influenzae; corresponding figures for non-Aboriginal children were 26% to 37% for S. pneumoniae and M. catarrhalis and 11% to 18% for H. influenzae. Non-Aboriginal children had higher carriage rates in winter than in summer, but season had little effect in Aboriginal children. Staphylococcus aureus carriage was highest under age 1 month (55% Aboriginal, 61% non-Aboriginal) and was always higher in non-Aboriginal than Aboriginal children.

CONCLUSIONS

Interventions are needed to reduce high transmission and carriage rates, particularly in Aboriginal communities, to avoid the serious consequences of OM.

Nasopharyngeal carriage of Streptococcus pneumoniae in Gambian villagers

BACKGROUND

To prepare for the introduction of a pneumococcal conjugate vaccine of restricted valency, we studied the nasopharyngeal carriage of Streptococcus pneumoniae in Gambian villagers.

METHODS

A cross-sectional survey was conducted in 21 villages after a census. We recorded demographic characteristics, information on medical history, and data on possible risk factors for carriage from subjects. We collected a nasopharyngeal swab specimen from each subject for isolation and serotyping of S. pneumoniae and for antibiotic susceptibility testing.

RESULTS

The prevalence of S. pneumoniae carriage among 2872 villagers was 72%. It was highest among infants (i.e., children aged <1 year; 97%); the rate was 93% among babies aged <1 month and decreased with increasing age (P<.001). Prevalence of carriage was linked to proximity to another village. Sixty-three percent of isolates recovered from children aged <5 years were covered by the 7-valent vaccine or were of a vaccine-related serotype, compared with 43% of isolates overall. Forty-three isolates (14.3%) tested were initially penicillin resistant; none had high-level resistance, and 4 had intermediate resistance. The rates of resistance to other antibiotics were as follows: trimethoprim-sulfamethoxazole, 39%; tetracycline, 32.3%; chloramphenicol, 6.3%; cefotaxime, 0.3%; and erythromycin, 0%. The rates were highest for isolates of vaccine serotypes.

CONCLUSIONS

Pneumococcal carriage rates among Gambian villagers are very high. A pneumococcal conjugate vaccine of restricted valency should reduce the pool of antibiotic-resistant pneumococci. The large reservoir of pneumococci of nonvaccine serotypes will require close monitoring when the vaccine is introduced.

Amoxicillin-sulbactam versus amoxicillin-clavulanic acid for the treatment of non-recurrent-acute otitis media in Argentinean children

Streptococcus pneumoniae (Sp) and Haemophilus influenzae (Hi) are the leading bacterial cause of acute otitis media (AOM), having the nasopharynx (NP) as their reservoir. In October 2001 we began a prospective, multicenter, randomized, evaluator blind study, comparing the efficacy of amoxicillin-sulbactam (Ax/S) and amoxicillin-clavulanic acid (Ax/C) for the treatment of non-recurrent AOM (nr-AOM). Both antimicrobial susceptibility (AS) to Ax/S and Ax/C from Sp and Hi carried by study children (aged 6-48 months with nr-AOM) and, clinical outcome after treatment with high dose of either Ax/C (7:1) or Ax/S (4:1) (amoxicillin dose: 80 mg/(kg day), b.i.d. for 10 days) were assessed. Nasal cultures (NCs) were taken at Day 0. Follow-up NCs, were done only for Sp carriers. On final analysis 247/289 pts (85.5%) were fully evaluable (120 Ax/S and 127 Ax/C). NP carriage rate of Hi and Sp at Day 0 was 32.2% (93/289 pts) and 28.7% (83/289 pts), respectively. Persistent Sp carriage was detected only in 2 pts. Hi betalactamase positive rate was 13% (12/93). MICs for Ax/S and Ax/C were identical when tested against Sp and Hi isolates (range < or = 0.016-1.0 and < or = 0.016-0.25 mg/L, respectively). Clinical efficacy at Days 12-14 and 28-42 were 98.3% (115/117) and 94.2% (97/103) for Ax/S; and 98.3% (115/117) and 95.1% (98/103) for Ax/C, respectively (pNS). We conclude, that Sp and Hi isolated from NCs of nr-AOM pts were highly sensitive to both drugs and correlated with high clinical efficacy rate.

Association between respiratory disease and bacterial and viral infections in British racehorses

Respiratory disease is important in horses, particularly in young Thoroughbred racehorses, and inflammation that is detected in the trachea and bronchi (termed inflammatory airway disease [IAD]) is more significant in this population in terms of impact and frequency than other presentations of respiratory disease. IAD, which is characterized by neutrophilic inflammation, mild clinical signs, and accumulation of mucus in the trachea, may be multifactorial, possibly involving infections and environmental and immunological factors, and its etiology remains unclear. This 3-year longitudinal study of young Thoroughbred racehorses was undertaken to characterize the associations of IAD and nasal discharge with viral and bacterial infections. IAD was statistically associated with tracheal infection with Streptococcus pneumoniae (capsule type 3), Streptococcus zooepidemicus, Actinobacillus spp., and Mycoplasma equirhinis and equine herpesvirus 1 and 4 infections, after adjustment for variation between training yards, seasons, and age groups. The association with S. pneumoniae and S. zooepidemicus was independent of prior viral infection and, critically, was dependent on the numbers of organisms isolated. S. pneumoniae was significant only in horses that were 2 years old or younger. The prevalence and incidence of IAD, S. zooepidemicus, and S. pneumoniae decreased in parallel with age, consistent with increased disease resistance, perhaps by the acquisition of immunity. The study provided evidence for S. zooepidemicus and S. pneumoniae playing an important etiological role in the pathogenesis of IAD in young horses.

Comparison of antibiotic resistance and serotype composition of carriage and invasive pneumococci among Bangladeshi children: implications for treatment policy and vaccine formulation

The nasopharyngeal carriage of Streptococcus pneumoniae is thought to pose a risk for invasive pneumococcal diseases, and the evaluation of carriage strains is thus often used to inform antibiotic treatment and vaccination strategies for these diseases. In this study, the age-specific prevalences, resistance to antibiotics, and serotype distributions of 1,340 carriage strains were analyzed and compared to 71 pneumococcal strains isolated from the cerebrospinal fluid of children under 5 years old with meningitis. Overall, the nasal carriage rate was 47%. One-fourth (26%) of the infants under 1 month of age and one-half (48%) of the infants under 12 months of age were colonized with S. pneumoniae. Rural children were colonized earlier than those from urban areas. Approximately one-fourth and one-half of the cases of pneumococcal meningitis occurred in the first 3 and 6 months of life, respectively. The respective rates of resistance for carriage and meningitis strains to penicillin (7 and 3%), cotrimoxazole (77 and 69%), and erythromycin (2 and 1%) were similar, whereas chloramphenicol resistance was lower among carriage strains (3%) than among meningitis strains (15.5%). The predominant serogroups of carriage and invasive isolates were variable and widely divergent. Thus, hypothetical 7-, 9-, and 11-valent vaccines, based on the predominant carriage strains of the present study, would cover only 23, 26, and 30%, respectively, of the serotypes causing meningitis. Further, currently available 7-, 9-, and 11-valent vaccines would protect against only 26, 43, and 48%, respectively, of these meningitis cases. In conclusion, while the surveillance of carriage strains for resistance to antibiotics appears useful in the design of empirical treatment guidelines for invasive pneumococcal disease, data on the serotypes of carriage strains have limited value in vaccine formulation strategies, particularly for meningitis cases.

Effect of a nonavalent conjugate vaccine on carriage of antibiotic-resistant Streptococcus pneumoniae in day-care centers

BACKGROUND

In the developed societies, day-care centers (DCCs) play an important role in the spread of antibiotic-resistant pneumococci both within the facility and from the facility to the community. This study was conducted to determine the effect of a nonavalent pneumococcal conjugate vaccine (PCV-9) on the carriage of antibiotic-resistant pneumococci in the DCC.

SUBJECTS AND METHODS

Healthy DCC attendees ages 12 to 35 months were randomized to receive either PCV-9 or a control vaccine (conjugate meningococcus C vaccine) in a double blinded manner. Nasopharyngeal Streptococcus pneumoniae cultures were obtained from each subject before vaccination, monthly during the first year of follow-up and every 2 to 3 months during the second year of follow-up. For each isolate the serotype and antibiotic susceptibility were determined.

RESULTS

A total of 132 and 130 evaluable toddlers received either PCV-9 or the control vaccine, respectively. In total 3748 cultures were obtained, of which 2450 (65%) were positive for S. pneumoniae. The resistance rates to penicillin, trimethoprim-sulfamethoxazole and erythromycin were 36, 35 and 16%, respectively. Resistance rates to > or =1 and > or =3 antibiotic categories were 52 and 9%, respectively. Antibiotic resistance was found mainly in the 5 serotypes included in the pneumococcal conjugate vaccines (6B, 9V, 14, 19F and 23F) and in 2 related serotypes (6A and 19A). In the vaccinated group a clear and significant reduction of the carriage rate of the serotypes included in the vaccine and the related serotype 6A as well as an increase in the carriage rate of the serotypes not included in the vaccine were observed. In parallel a significant decrease in carriage rate of antibiotic-resistant pneumococci was observed. The reduction of carriage of antibiotic-resistant pneumococci was seen in all age windows but was greater in the age window <36 months.

CONCLUSIONS

The carriage rate of antibiotic-resistant S. pneumoniae, including multiply resistant S. pneumoniae, in DCC attendees is high. Pneumococcal conjugate vaccines seem to be an important tool for reducing the carriage rate of antibiotic-resistant pneumonia in DCCs.

Report from a WHO Working Group: standard method for detecting upper respiratory carriage of Streptococcus pneumoniae

BACKGROUND

Numerous studies evaluating the efficacy of conjugate pneumococcal vaccines are being conducted or planned throughout the world. Some of these studies are evaluating the effect of vaccine on nasopharyngeal (NP) carriage.

METHODS

The World Health Organization established a Working Group comprised of representatives from these trials and other NP colonization experts to establish core, standardized methods for the study of pneumococcal NP colonization that could be used in these trials. The intent was to reduce or eliminate variability in key methods which themselves could contribute to variability of observed pneumococcal NP colonization. In this way variability of vaccine effects between trials on NP colonization could more easily be analyzed for population or vaccine differences without the confounding effect caused by differences in study methodology.

RESULTS

This paper presents the evidence base supporting the need for standardized NP colonization study methods, the methods themselves (Core Consensus Methods), including collection techniques, culture media, equipment, serotyping, storage of specimens and transport of isolates agreed on by the Working Group as well as a discussion of research priorities.

CONCLUSIONS

The Core Consensus Methods provide a common methodology to conduct pneumococcal NP colonization studies with minimum interstudy method variability. The intention is to allow more meaningful comparisons of study results from conjugate pneumococcal vaccine trials.

A household survey on morbidity and treatment of acute respiratory infections in communities in Vietnam

OBJECTIVE

To ascertain the extent of under-utilization and insufficiency or inappropriateness in provision of health services as one of the possible causes of high mortality from pediatric pneumonia in pilot areas in Vietnam.

METHOD

The household survey on morbidity and treatment of acute respiratory infections, simple cough, and cold and pneumonia, was conducted in two communities with 10% sampling of the child population.

RESULTS

Both under-treatment of "fast breathing", a proxy for pneumonia, and over-treatment of simple cough and cold with antimicrobials by health workers, mothers, and private practitioners were common.

CONCLUSIONS

A household survey on morbidity and treatment was found to be useful to clarify actual practices in the treatment of acute respiratory infections in the community, which cannot be obtained by mere interview with health workers or mothers. Since a change of knowledge did not automatically lead to change of practice, the training of health workers, health education of mothers and provision of antimicrobials at village health stations would not guarantee improved practice of health workers and mothers. Therefore, constant supervision for health workers, continued health education of mothers and involvement of private practitioners are needed to improve the situation.

Carriage of gram-negative bacilli in young Brazilian children with community-acquired pneumonia

BACKGROUND

Gram-negative bacilli are not infrequently encountered as etiologic organisms of pneumonia in children in warm-climate countries.

OBJECTIVES

To investigate the nasopharyngeal carriage rate and antimicrobial susceptibility patterns of gram-negative bacilli colonizing children with community-acquired pneumonia in Fortaleza, Brazil.

METHODS

A single nasopharyngeal specimen was collected from children 2 months to 5 years of age presenting at one of the three children's hospitals in Fortaleza and fulfilling the World Health Organization criteria for pneumonia. Randomly recruited healthy children from public daycare centers and immunization clinics served as controls.

RESULTS

The study included 912 children, 482 (53%) with pneumonia and 430 (47%) controls. Aerobic gram-negative bacilli were seen in 79 (16%) of the 482 children with pneumonia and 51 (12%) of the 430 healthy controls. Nonfermentative gram-negative bacilli were seen in 85 (18%) of children with pneumonia and 54 (13%) of healthy controls. Neither gender, nutritional status, season, previous hospital admission nor antibiotic use was associated with carriage with gram-negative bacilli. However, pneumonia was associated with increased carriage, whereas concomitant colonization with Streptococcus pneumoniae or Haemophilus influenzae was associated with decreased carriage with gram-negative bacilli. Only 36% of all Escherichia species and 76% of all Klebsiella isolates were susceptible to cotrimoxazole; 90% of all Acinetobacter species were susceptible to gentamicin.

CONCLUSION

Nasopharyngeal carriage with gram-negative bacilli, in particular with Acinetobacter species, is common and associated with a clinical diagnosis of community-acquired pneumonia in children in Fortaleza, Brazil.

Modelling of endemic carriage of Haemophilus influenzae in Aboriginal infants in Northern Australia

Aboriginal infants and children in rural communities in Northern Australia have high rates of nasopharyngeal carriage of nonencapsulated Haemophilus influenzae (NCHi), with positive swab rates of 76%. In this population, the acquisition of NCHi from soon after birth is associated with the onset of otitis media and with muco-purulent nasal discharge, while the long-term persistence of NCHi carriage is associated with the acquisition and turnover of large numbers of antigenically diverse strains. Mathematical models have been fitted to data on the acquisition and loss of encapsulated strains of H. influenzae and 43 different strains of NCHi in 10 children followed from early infancy for up to 2 years. Subject to plausible assumptions, the preferred model estimated the mean time to acquisition of a H. influenzae strain to be 7 days after first becoming exposed after birth. For an infant already carrying H. influenzae, each additional strain was acquired after a mean waiting period of 45 days. On average, 1.50 different strains of H. influenzae were detected in four colonies routinely typed from each positive swab, but it was estimated that another 2.55 strains were 'hidden' behind these more frequent strains. With an average of 4.05 strains per carrier, it was estimated that each strain was carried for an average of 137 days, although detected on only 37% of occasions. Thus we have developed mathematical models that provide estimates for duration of colonisation, time to colonisation, and number of colonising strains in a population in which H. influenzae is highly endemic, characterised by sequential and concurrent carriage of multiple strains in each infant.

Streptococcus pneumoniae nasopharyngeal carriage prevalence, serotype distribution, and resistance patterns among children on Lombok Island, Indonesia

Few data exist on childhood pneumococcal carriage prevalence, serotype distribution, and resistance patterns for Indonesia, the world's fourth most populous country. During August 1997, nasopharyngeal samples were collected from a population-based, island-wide sample of 484 healthy children (age, 0-25 months) from Lombok Island, Indonesia. Two hundred twenty-one pneumococcal isolates were identified, for a carriage prevalence of 48%; 66% of isolates were of serogroup or serotype 6, 23, 15, 33, or 12. All isolates were susceptible to penicillin and cefotaxime. Twelve percent of the isolates were nonsusceptible to sulfamethoxazole or chloramphenicol and 4% were nonsusceptible to both of these drugs. Nonsusceptible organisms were most frequently serogroup or serotype 6, 12, and 33. Lombok has a moderate pneumococcal carriage prevalence and a relatively low proportion of resistant isolates. At least 3 of the 5 most common serogroups and serotypes and 2 of the 3 most common nonsusceptible serogroups and serotypes are not included in the current 7-valent pneumococcal conjugate vaccine.

Marked differences in pneumococcal carriage and resistance patterns between day care centers located within a small area

Carriage rates of Streptococcus pneumoniae and their antibiotic resistance, capsular types, and genetic patterns were studied among 264 children aged 12-35 months attending 8 day care centers located within a 2.5-mile radius in the same city. Nasopharyngeal cultures were obtained within a 2-month interval from all 264 children. Significant differences in each of the studied characteristics were found between day care centers, and each day care center had a unique pattern of the carried pneumococci. Our findings show that day care centers are independent microenvironments and emphasize their role in the transmission and augmentation of antibiotic-resistant S. pneumoniae in the community.